The present invention relates generally to resilient pads which are placed under sports floor systems such as gymnasiums, exercise floors, and the like. More particularly, the invention relates to such a pad which is designed to provide desirable response and shock absorption characteristics under a wide variety of floor loads.
It is generally known to provide cushioning pads under a sports flooring system in order to provide resiliency to the floor. In such known systems, the amount of cushioning provided by the pads is generally controlled by the durometer, i.e., the hardness, of the pads. There are both advantages and disadvantages to using either hard or soft pads.
Specifically, in sports such as basketball and racquetball, it is important that the floor be relatively stiff, so that the ball bounces back easily and uniformly throughout the floor. High durometer (hard) resilient pads produce a floor having preferred ball response characteristics. However, such hard pads do not deform easily when the floor is placed over an uneven base substrate. If there is a loss of contact between a particular pad and the base substrate, a "dead spot" will be created, causing very poor ball response at that point. Furthermore, hard pads provide little shock absorption, and have a greater potential to cause harm to the athlete. This problem is especially severe when heavy loading occurs from a number of athletes performing in close proximity to each other.
Low durometer (soft) resilient pads provide greater shock absorption and hence provide a higher level of safety to the athlete. These resilient pads also provide for high deflection under light loads, and hence can conform to uneven base substrates, reducing the problem of "dead spots." However, floors employing such soft pads do not produce desirable ball response characteristics under normal loading conditions, and thus are not highly suitable for sports such as basketball and racquetball. Furthermore, soft pads are prone to "compression set" which is a permanent change in profile after the pad has been subjected to high loads for a long period of time. Such compression set can occur in areas where bleachers, basketball standards, or other gymnasium equipment are likely to be placed for periods of time.
Numerous attempts have been made to design a resilient pad which will produce a flooring system having the desirable characteristics of both hard and soft resilient pads, without the disadvantages of each. One such example is U.S. Pat. No. 4,890,434 to Niese. Niese discloses a pad having a frusto-conical shape with an interior relieved area which increases deflectability.
The resilient pad of Niese, however, has several disadvantages. First, the pad provides only a limited change in the response characteristics as compared to a standard pad. Second, the resiliency of the pad cannot easily be changed, for example, in order to customize the pad to a particular floor system. Third, the pad is relatively expensive to produce, as the pad is complex in shape and must be produced in a mold.